Pilomatricoma can differentiate not only towards hair matrix and hair cortex, but also follicular infundibulum, outer root sheath and hair bulge

Abstract

Pilomatricoma is believed to differentiate towards the hair matrix and hair cortex. To elucidate the origin of differentiation in pilomatricoma, we studied the expression of epithelial keratin (K) and filaggrin (filament aggregating protein) in pilomatricoma. An immunohistochemical study has been made of 53 cases of pilomatricoma using 10 monospecific anti-keratin antibodies and anti-filaggrin antibody. Basophilic cells, transitional cells and shadow cells did not react with epithelial keratins and filaggrin antibodies as well as hair matrix and hair cortex. Instead, infundibular-type epithelium was positive for K1, K10 and filaggrin. Epithelium showing trichilemmal keratinization was positive for K14 and K16. The hair bulge-like structure was positive for K19. The differentiation of pilomatricoma is diversified, and is heterogeneous in epithelial keratin and filaggrin expression. Our results for keratin and filaggrin expression suggested that pilomatricoma can differentiate not only towards hair matrix and hair cortex, but also follicular infundibulum, outer root sheath and hair bulge.Key words: differentiation -filaggrin -keratin -pilomatricoma Please cite this paper as: Pilomatricoma can differentiate not only towards hair matrix and hair cortex, but also follicular infundibulum, outer root sheath and hair bulge. Experimental Dermatology 2009; 18: 734-737.

Shadow Cell Differentiation: A Comparative Analysis of Modes of Cell Death with Apoptosis and Epidermal/Trichilemmal Keratinization

“…There are various components showing TD or cell death inside the nodules by one of the following routes [42, 43]: (a) SCD, the main route of cell death/differentiation, (b) conventional apoptosis, and (c) EK/TK (Fig. 2).…”

“…2, inset). TK is rarely observed in PMX [43]. The nodule containing equal amounts of SCD and EK components is called an infundibular matrix cyst or hybrid cyst [44].…”

Epidermal cyst with pilomatricoma (follicular hybrid cyst): Immunohistochemical study with epithelial keratins and filaggrin

“…Keratin is found as intermediate‐sized filaments and is a differentiation marker of epithelial tumor 5 . Filaggrin, filament aggregating protein, is a major component of keratohyaline granules and is a marker of terminal differentiation 6 .…”

“…The patient had no familial history of Gardner’s syndrome and did not have colonic polyposis. Excised specimens underwent immunohistochemical study with epithelial keratins and filaggrin using the labeled streptavidin biotin (LSAB) method as reported previously 5 . The anti‐keratin antibodies and anti‐filaggrin antibody used were 34βB4 (K1), LP5K (K7), LP3K (K8), HP1 (K10), LL002 (K14), LHK15 (K15), LL025 (K16), E3 (K17), 5D3 (K18), b170 (K19) and 15C10 (filaggrin) (all from Novocastra Laboratories, Newcastle‐upon‐Tyne, UK) 5 …”

Pilomatricoma of the upper arm in an orthopaedic clinic

“…Over a century after its introduction, our basic knowledge of this uncommon tumor is still developing. In 2009 Kurokawa et al 10 showed that pilomatricomas could differentiate not only toward the hair follicle matrix cells but also toward the hair cortex, infundibulum, outer root sheath, and hair bulge.…”